Docs · Start here

What spck.dev is, and how the pieces fit

spck.dev is an independent, open-source conformance tester for UCP — the open standard for agentic commerce (ucp.dev). It has two sides: it checks merchant servers against the spec, and it tests shopping agents against reference stores. It is spec-cited and reproducible throughout; this page lays out the pieces, then shows you how to run it.

Check your store → Test an agent →

The pieces

Two sides, a shared reference layer, and an ongoing read on the ecosystem.

For merchants

Check your store — an instant, no-writes conformance read from the browser.
CLI & full suite — the deep run, including write paths, against a store you own.
CI Action — gate conformance on each push.

For agent builders

Test a shopping agent — the buy-side checks a server suite misses.
Interop sandbox — watch a correct agent, then a broken one.

Reference

Coverage matrix — the normative MUSTs, accounted and live.
Check register — each check, cited to its spec clause.
Grading rubric — what pass, deviation, and not-tested mean.

Reading

State of UCP — a monthly, data-backed read on real UCP adoption.

Install and run the full suite

Install from PyPI, scaffold a config tailored to what your store declares, then run it against your own store. The full suite exercises the checkout, cart, and order write paths that the instant web check can't reach — so point it at a store you own, never someone else's.

pip install spck-conformance
spck-conformance --server https://store.example.com --init merchant.json
spck-conformance --server https://store.example.com --config merchant.json

On a deviation it shows the requirement next to your actual response. It runs the checks your store declares support for, and reports anything it can't reach as not-tested rather than a silent pass. Runs on Python 3.9+.

Test a shopping agent

The same package tests the buy side. Point a shopping agent at a bundled reference store that behaves correctly and one that misbehaves on purpose — locally, in a single command.

spck-conformance --agent

Each agent check passes a correct agent and catches a broken one. Watch recorded runs in the sandbox →

Gate it in CI

Add the GitHub Action so conformance runs on each push. It fails the build on a MUST deviation and writes a JUnit report.

- uses: vishkaty/ucp-conformance@main
  with:
    server: https://store.example.com
    config: merchant.json   # optional

What gets checked

The full CLI suite covers, across REST and MCP transports:

Discovery and profile structure
Checkout lifecycle — create, update, complete, cancel
Cart and order retrieval
Fulfillment and shipping
Discounts and consent
Payment, including AP2 mandates
HTTP message signatures
OAuth 2.0 identity linking
Order webhooks and the totals invariants

Each check is anchored to the official ucp-schema validator and cites the spec clause it enforces.

Spec versions

Tests run against the pinned UCP spec versions:

2026-04-08
2026-01-23
2026-01-11